1. Field of the Invention
The present invention relates to a triangle wave generator. More particularly, the present invention relates to the spread spectrum mechanism of a triangle wave generator.
2. Description of the Related Art
Periodic waveforms such as clock and triangle wave signal are very common in modern electronic circuits. In order to prevent electromagnetic interference (EMI) caused by harmonic of one single frequency, spread spectrum skill is applied. Spread spectrum spreads the frequency of periodic waveforms within a specific range so that their energy is distributed over the frequency spectrum. EMI can be prevented in this way.
Most spread spectrum methods are developed for clock signals, but they are unsuitable for triangle wave signals. These methods introduce nonlinear distortion, for example, a triangle wave such as the signal 101 in FIG. 1, would become a distorted triangle wave signal such as the signal 102 in FIG. 1, after spreading spectrum. This distortion comes from continuous frequency disturbance, that is, when a slope part of the triangle wave is outputted, its output frequency keeps changing. Consequently, the linearity of the slope part is lost. The distortion is undesirable in some applications.